1. FIELD OF THE INVENTION
The present invention relates to a silver halide photographic light-sensitive material containing a novel compound capable of releasing a development inhibitor.
2. DESCRIPTION OF THE PRIOR ART
It is known that a compound which provides a development inhibitor in an amount depending on the optical density of an image formed upon development can be used by addition to a photographic light-sensitive material. Such a compound generally releases a development inhibitor by reaction with the oxidation product of a color developing agent. Typical development inhibitor releasing (DIR) compounds of this type include the so-called DIR couplers, the active site of which contains a group which exhibits a development inhibiting action when it is split from the active site. DIR couplers form dyes by coupling with the oxidation product of a color developing agent and release development inhibitors. Compounds such as those disclosed in U.S. Pat. Nos. 3,227,554, 3,701,783, 3,615,506, 3,617,291 and the like are known DIR couplers.
DIR couplers are employed for the purpose of controlling the image tone, reducing graininess of the image, improving sharpness of the image due to edge effects, improving color reproduction due to interlayer effects, and the like as is well known from the disclosure in the above-mentioned patent specifications.
However, in many cases, DIR couplers as described in U.S. Pat. No. 3,227,554, etc., do not exert the desired inhibiting effect resulting in a degradation of the photographic properties and storage properties because the dye yield upon development adversely affects color reproduction unless the proper type of coupler residue and the proper amount of coupler are precisely chosen, and a convenient selection of a coupler residue for color reproduction restricts the permissible reactivity of the oxidation product of the color developing agent and the coupler. In addition, DIR couplers of this type have various disadvantages such as poor stability against ageing, they often exhibit a desensitization effect, they produce mottle resulting from contamination of the developer solution and the like.
The so-called non-color forming type of coupling compounds were developed with the intention of eliminating these disadvantages, which coupling compounds form essentially colorless products or colored products, whose color, however, change and become essentially colorless in the course of photographic treatment upon undergoing a coupling reaction with the oxidation product of a color developing agent, and also yield a development inhibitor at the same time. Known compounds of this type are disclosed in U.S. Pat. Nos. 3,632,345, 3,928,041, 3,958,993 and 3,961,959 and the like. While these compounds have advantageous properties, they also have some drawbacks. For example, the stain resulting from the products formed by the reaction of these compounds and the oxidation products of color developing agents is one drawback of the compounds. Their most serious drawback, however, is the low reactivity of the coupling compounds with the oxidation products of color developing agents. Accordingly, a large amount of these compounds must be employed because of their low reactivity and this results in a decrease in the photographic properties and a reduction in shelf life. Further, all of the compounds disclosed in the above-described U.S. patent specifications yield mercapto group-containing compounds by reacting with the oxidation product of a developing agent. When compounds of this type are employed for producing multilayer color photographs, the resulting development inhibiting agent tends to remain in the layer in which the compound was incorporated, i.e., it diffuses only with difficulty into other layers. Therefore, these compounds contribute only slightly to the so-called interlayer effect, resulting in unsatisfactory color correction, and resistance to desilvering in the bleaching step tends to occur. In order to improve these drawbacks, the compounds as described in U.S. Pat. No. 3,933,500 are known. While the photographic properties are improved to a certain extent, it is desirable to provide a DIR coupler which has further improved properties in that the DIR coupler has an extremely high reactivity with the oxidation product of a color developing agent so as to yield sufficient image improving effects with the use of a small amount thereof, and in that the color of the compound which is formed by the reaction of the DIR coupler with the oxidation product of a color developing agent does not substantially affect the finished color image when the DIR compound is used in a light-sensitive material.